Damping control



Sept. 20, 1955 J, w, BAMFORD ET AL DAMPING CONTROL 2 Sheets-Sheet 1 Filed May 23, 1952 INVENTORS JOHN W. BAMFORD, ROBERT E. FREDERICKS 5 & ROBERT B. KEE 5 ATTORNEY p 1955 J. w. BAMFORD ET AL 2,718,149

DAMPING CONTROL Filed May 23, 1952 2 Sheets-Sheet 2 INVENTORS JOHN W. BAMFORD, ROBERT E. FREDERICKS 8- ROBERT B. KEES BY flail 8.7M

ATTORNEY United States Patent DAMPING CONTROL John W. Bamford, Manhattan Beach, Robert E. Fredericks, Santa Monica, and Robert B. Kees, Pacific Palisades, Calif.

Application May 23, 1952, Serial No. 289,688

21 Claims. (Cl. 745.5)

This invention relates to a damping control for rotatable bodies.

The primary object of this invention is to provide an improved damping control for a rotatable body which is substantially constant in its effect on the body.

A more specific object of this invention is to provide an improved damping control for a rotatable body immersed in a fluid in which the effect of the control on the body is maintained substantially constant regardless of the effect of temperature changes on the viscosity of the fluid.

A further object of this invention is to provide a damping control for a rotatable body immersed in a fluid in which the viscous shear drag of the control on the body is maintained substantially constant by a thermal responsive element coacting with an eccentric to compensate for viscosity changes in the fluid under varying temperature conditions.

A more particular object of this invention is to provide a linear damping control for a rotatable body immersed in a fluid.

With the foregoing and other objects in view, the invention resides in the following specification and appended claims certain embodiments and details of construction of which are shown in the accompanying drawings, in which:

Figure l is a perspective view of the basic elements of the invention;

Figure 2 is a diagrammatic view of the elements of the invention for purposes of discussion, and

Figure 3 is an elevational view of the invention as utilized on a practical commercial unit.

Referring now more particularly to Fig. l, a rotatable body 1, constituting a member to be damped, as shown withdrawn from its casing 2. The casing is provided with confining end sections, not shown, and is filled with a suitable damping fluid, the character of which is not important here. A shroud 3 is pivotally connected to the casing end section (not shown in Fig. 1) about the axis 4. The rotatable body 1, as shown, has a cylindrical surface to which the arcuate surface 5 of the shroud 3 conforms. The end of shroud 3 is provided with a rigid follower arm 6 which engages the cam surface 7 of an eccentric 8. The eccentric 8 is mounted for free rotation about the axis of rotation 9 of the body 1. As shown in Fig. 1 the eccentric is shown freely carried on stationary spindle 10 which is suitably secured to the end section of the casing (not shown). Connected at one end to a projection 11 on the eccentric 8 is a thermal responsive element 12. The other end 13 of element 12 is secured to spindle 10 by any suitable means.

The type of thermal responsive element shown is a spirally wound bismetallic strip which will accurately respond to varying temperature conditions by tending to expand or contract as the case may be. It is immaterial whether the end 13 of element 12 is secured to the spindle, to a bearing supporting the body mounting the spindle (not shown in Fig. 1), or to a part of the casing end section. The important consideration is that the element be secured to the casing at tric at the other end.

the v e body 1 together with the damping fluid confined iri said i order to compensate for the varying viscosity ftheda fluid under temperature changes; necessary h spacing between the shroud an body"'-be' aried. This variation in spacing is accomplishedby tli ffeely mounted eccentric 8 coacting with'tli herina responsive element 12. 1

Thus in Fig. 2 upon an increaseinteinperature which results in a decrease in fluid viscosityg 'if necessar' that the spacing between the shroud Sfandody decreased to have the same predetermined' shear drag or damping effect as prior to said temperature cha'ng' The thermal responsive element 12 will move th eccent c 8 clockwise and the follower arm 6 will ride'-down the cam surface 7 to reduce the spacing between-the bo'dy' lfand the shroud 3 by permitting the shroud sto pivotfin'wardly F about its pivot axis 4. The reverserof this operation is effective upon decreases in temperature'twhich end to increase the viscosity of the fluid.

The construction of the shroud, the :cam..and-:th thermal responsive element and theirvrplacmentvwithin the casing 2 are a matter of choice'glitsonl'ya'beingr'essential that the three parts coact in response .to temperature changes affecting the viscosity oft'theizdarnping zfluid to maintain a predetermined dampingzcontrol' on the body 1. Referring now to Fig. 3 the damping'controliisishown as applied to a rate gyroscope asaused inraircraftA-The rotatable body to be damped is thesgyro, gimbal 14'S'which is cylindrical in form. Housed within: ;said;gimbal.are the rotor and other parts of such gyroscopes, :the construction of which forms no part of this inventio The-.;gimbal 14 is carried in a fluid-filled casing I15;;.a-n :shown in Fig. 3 as Withdrawn therefrom 'for;purposes.;-of clarity. The front end section of the casing is gShQ carries a bearing (not shown) for; supporltlnggthe pivm spindle at the forward end of gimbal.- A similar bearing-17 is provided f rear section of the casing (not sh wn) andthis bearing supports the rear pivot spindle o f the gimbalfll Th the gimbal 14' is mounted for free rotation, withi s'the fluid-filled casing 15. f

In order to increase the utilit an curacy of;;rate gyroscopes, it is desirable to providea damping control for such instruments which is unaected by the'c'hanges in temperature to which aircraft are subjec }In;Eig. 3 such a control is provided by elementssimilargto,those in Figs. 1 and 2. A plurality of shrouds- .18,;havingsubstantially arcuate surfaces 19, are ;pivotally; secured to front casing section 16 by pivot,tpin s il eggtending.into pivot bosses 22 positioned about--th SCCtlOll 16. l

A resilient element 23, which is,pre ferably:a;1stiff wire spring, is secured at one end tqeach shroud;.18.,at; 24 by any suitable means and at the other end i25 to the end section 16 at 26. The purpose of the ..elem ents 23 is to bias the shrouds toward the bal 14. It is quite obvious that other resilient biasin ements having different designs and points o ,connection:;.between the casing and the shrouds could be utilized, Theimportant point is that the shrouds, biased ,toward the rotatable body or gimbal 151, so that th v between biasing means and the automa ic sive means to be described, may o c cu ing between the shrouds and the body.

. tions on such indicating needles. .damping control for ,such instruments as rate gyroscopes Mounted on the rear pivot spindle of gimbal M'for free rotation thereon, is an eccentric 27 having a plurality of cam' surfaces 28 all identical in character. Secured to the eccentric 27 at 29 by any suitable means is a spirally wound. thermal responsive element 30. The inner end 31 of element 30 is connected by suitable means .to the supporting bearing 17 which is secured to the rear casing section as previously described.- Provided-at the free extremities 32 of shrouds 18 are-rigid follower arms 33 each of which engages a cam surface 28 whenin operative positionunder the resilient action of biasing springs The operation of the unit of Fig-.3 is identical to that described for Figs. 1 and 2.' Theonly difference resides in the structure of Fig.-3-where, due to'a plu- .ttaininguaccurate .instrumentyreadings by aiding in the prevention of overshooting.of an indicating needle and in preventingor substantially reducing the effect of vibra- The vmost desirable is one which is linearin character. In the present invention it is seen that the shroud position is varied to compensate for changesin fiuidviscosity .to maintain a predetermined shear: drag damping; effect on the gimbal.

,Whether the damping is linear or not depends on the shape of the cam' surfaces and a damping control other than linear in character; undertvarioustemperature conditions may beobtainedby providing any desirable cam surfaces on the eccentric.

- The invention resides in the basic elements of the damp ing; control and their coaction in obtaining an effective I damping control of a rotatable body and not necessarily in their exact mode of construction and placement. It is readily foreseen that the exact structure as shown and described is adaptable to structural modifications. We claim as ourinvention:

1. A damping control for a rotatable body immersed in a fluid-filled casing comprising a shroud pivotally connected to the casing and being biased to a position adja cent' said rotatable body, a cam mounted for free'rotation about the axis of the rotatable body, a follower arm extending-from the freeend of saidshroud andengaging said. cam, and thermal responsivemeans to move said cam and consequently the follower arm in response to temperature changes varying the viscosity of the fluid to thereby vary the position of the shroud relative to the rotatable body to maintain a predetermined damping effect on the rotatable body.

2. A damping control for a rotatable body immersed in a fluid filled casingcomprising-a-plurality' of shrouds pivotally connected to the casing and-being biased to a position adjacent said rotatable body, aneccentric member, including a plurality of identical cam surfaces, mounted for free rotation about the axis-of the'rota'table body, a follower'armextending from the free end of each of said shrouds and engaging a cam surface of the eccentric member, and thermal responsive means to move said eccentric member and-consequently the follower arms in response to temperature changes causing variations in the viscosity of the fluid to thereby vary the positions of the shrouds relative to the-rotatable body to maintain a predetermined damping eifect on the rotatable body.

3. A damping control for a rotatable bodyimmersed in a fluid-filled casing-comprising a shroud pivotally connected to the casing and being biased to a position adjacent said rotatable body, a spindle extending from said body and rigidly secured thereto, a' casing mounted bearing for supporting said spindle, a cam mounted for free rotation on said spindle, a follower arm extending from the free end of saidshroud and engaging said'cam, and

thermal responsive means connected between said bearing and said cam to move said cam and consequently the follower arm in response to temperature changes affecting the viscosity of the fluid to thereby vary the position of the shroud relative to the rotatable body to maintain a predetermined damping eifect on the rotatable body.

4. A damping control for a rotatable body immersed in a fluid-filled casing comprising a shroud pivotally connected to the casing and being biased to a position adjacent said rotatable body, a spindle extendingfrom said body and rigidly secured thereto, a casing mounted hearing for supporting said spindle, a cam mounted for free rotation on said spindle, a follower arm extending from the free end of said shroud and engaging said cam, and a spiral thermostatic element connected at its inner end to the bearing and at'its outer end to said cam to move said cam and consequently the follower arm in response to temperature changes affecting the viscosity of the fluid to thereby vary the position of the shroud relative to the rotatable body to maintain a predetermined damping effect on the rotatable body.

5. A damping control fora rotatable body immersed in a fluid-filled casing comprising a plurality of shrouds pivotally connected to the casing and beingbiased to a position adjacent said rotatable body, a spindle extendingfrom said body and rigidly secured thereto, a casing mounted bearing for supporting said spindle, an eccentric member including a plurality of identical cam surfaces mounted for free rotation on said spindle, a follower arm extending from the free end of each of said shrouds and engaging a cam surface of the eccentric member, and thermal responsive means connected between said bearing and said eccentric'member to move said member and consequently the follower arms in response to temperature changes affecting the viscosity of the fluid to thereby vary the positions of the shrouds relative to the rotatable body to maintain a predetermined damping effect on the rotatable body.

6. A damping control for a rotatable body immersed in a fluid-filled casing comprising a plurality of shrouds pivotally connected to the casing and being biased to a position adjacent said rotatable body, a spindle extending from said body and rigidly secured thereto, a casing mounted bearing for supporting said spindle, an eccentric member including a plurality of identical cam surfaces, mounted for free rotation on said spindle, a follower arm extending from the free end'of each of said shrouds and. engaging aicam surface on the eccentric member,

and a spiral thermostatic element connected at its inner end to the bearing and at its outer end to said eccentric member to move said member and consequently the follower arms in response to temperature changes aifecting the viscosity of the fluid to thereby vary the positions of the shrouds relative to the rotatable body tomaintain a predetermined damping eifect on the rotatable body.

7. A damping control for a rotatable body immersed in a fluid-filled casing comprising a shroud pivotally connected to the casing and positioned adjacent said rotatable body, a spindle extending from said body and rigidly secured thereto, a casing mountedbearing supporting said spindle, a cam mounted for free rotation on said spindle, a follower arm extending from the free end of said shroud and engaging said cam, resilient Y means positioned between said casing and said shroud to maintain the engagement of said follower arm with said cam, and thermal responsive means connected between said bearing and said cam to move said cam and consequently the follower arm against the action of said resilient means in response to temperature changes affecting the viscosity of the fluid to thereby vary the 7 position of the shroud relative to the rotatable body to maintain a predetermined damping eifect on the rotatable body.

8. A damping control for a rotatable body-immersed air rame in'a fluid-filled casing comprising a plurality of shrouds said arms engaging one of said cam surfaces, resilient means positioned between said casing and said shroud to maintain the engagement between said arms and said cam surfaces, and thermal responsive means connected between said bearing and said eccentric to move said eccentric and consequently the follower arms against the action of said resilient means in response to temperature changes affecting the viscosity of the fluid to thereby vary the positions of the shrouds relative to the rotatable body to maintain a predetermined damping effect on the rotatable body.

9. A damping control for a rotatable body immersed in a fluid-filled casing comprising a shroud pivotally connected to the casing and being biased to a position adjacent said rotatable body, a spindle extending from said body and rigidly secured thereto, a casing mounted bearing for supporting said spindle, a cam mounted for free rotation on said spindle, a follower arm extending from the free end of said shroud and engaging said cam, and thermal responsive means connected between the casing and said cam to move said cam and consequently the follower arm in response to temperature changes affecting the viscosity of the fluid to thereby vary the position of the shroud relative to the rotatable body to maintain a predetermined damping effect on the rotatable body.

10. A damping control for a rotatable body immersed in a fluid-filled casing comprising a shroud pivotally connected to the casing and being biased to a position adjacent said rotatable body, a spindle extending from said body and rigidly secured thereto, a casing mounted bearing for supporting said spindle, a cam mounted for free rotation on said spindle, a follower arm extending from the free end of said shroud and engaging said cam, and

a spiral thermostatic element connected at its inner endto the casing and at its outer end to said cam to move said cam and consequently the follower arm in response to temperature changes affecting the viscosity of the fluid to thereby vary the position of the shroud relative to the rotatable body to maintain a predetermined damping effect on the rotatable body.

11. A damping control for a rotatable body immersed in a fluid-filled casing comprising a plurality of shrouds pivotally connected to the casing and being biased to a position adjacent said rotatable body, a spindle extending from said body and rigidly secured thereto, a casing mounted bearing for supporting said spindle, an eccentric with a plurality of cam surfaces mounted for free rotation on said spindle, a follower arm extending from the free end of each of said shrouds, each arm engaging one of said cam surfaces of the eccentric, and thermal responsive means connected between the casing and said eccentric to move said eccentric about the spindle and consequently the follower arms in response to temperature changes affecting the viscosity of the fluid to thereby vary the positions of the shrouds relative to the rotatable body to maintain a predetermined damping effect on the rotatable body.

12. A damping control for a rotatable body immersed in a fluid-filled casing comprising a plurality of shrouds pivotally connected to the casing and positioned adjacent said rotatable body, a spindle extending from said body and rigidly secured thereto, a casing mounted bearing for supporting said spindle, an eccentric with a plurality of cam surfaces mounted for free rotation on said spindle, a follower arm extending from the free end of each of said shrouds, each arm engaging one of said cam surfaces of the eccentric, resilient means positioned between said shrouds and said casing to maintain the engagement of the follower arms on said cam surfaces, and thermal responsive means connected between the casing and said eccentric to move said eccentric about the spindle and consequently the follower arms in response to temperature changes affecting the viscosity of the fluid to thereby vary the positions of the shrouds relative to the rotatable body to maintain a predetermined damping effect on the rotatable body.

13. A damping control for a rotatable body immersed in a fluid-filled casing comprising a plurality of resiliently biased shrouds pivotally connected to the casing at one extreme thereof, said shrouds having their free ends positioned along but out of contact with the surface of said rotatable body, and means coacting between the other extremeof said casing and the free ends of said shrouds to vary the spacing between the shrouds and said body.

14. A damping control for a rotatable body immersed in a fluid-filled casing comprising a resiliently biased shroud pivotally connected to the casing at one extreme thereof, said shroud having its free end positioned along but out of contact with the surface of said rotatable body, and coacting eccentric and thermal responsive means positioned at the other extreme of the casing to vary the spacing between the shroud and said body.

15. A damping control for a rotatable body immersed in a fluid-filled casing comprising a plurality of resiliently biased shrouds pivotally connected to the casing at one extreme thereof, said shrouds having their free ends positioned along but out of contact with the surface of said rotatable body, and coacting eccentric and thermal responsive means positioned at the other extreme of the easing to vary the spacing between the shrouds and said body.

16. A damping control for a rotatable body immersed in a fluid-filled casing, said body having a cylindrical surface comprising a resiliently biased shroud pivotally connected to the casing at one extreme thereof, the free end of said shroud having an arcuate surface conforming to the cylindrical surface of the body and being positioned along but out of contact with said cylindrical surface, and means coacting between the casing and the free end of said shroud to vary the spacing between the arcuate surface of the shroud and the cylindrical surface of the body.

17. A damping control for a rate gyroscope including a rotatable gimbal, comprising a fluid-filled casing for housing said gimbal, at least one resiliently biased shroud pivotally secured to one extreme of the casing, the free end of said shroud having a surface conforming to the surface of the gimbal and being positioned along but out of contact with said gimbal, and means coacting between the casing and the free end of said shroud to vary the spacing between the gimbal and the shroud.

18. A damping control for a rotatable body immersed in a fluid filled casing comprising movable means connected to the casing and positioned adjacent said rotatable body, means connected between the casing and the movable means to bias said movable means toward said rotatable body, and means to automatically vary the position of the movable means in conjunction with said biasing means to compensate for changes in fluid viscosity to maintain a predetermined damping effect on the rotatable body.

19. A damping control for a rotatable body immersed in a fluid-filled casing comprising movable means connected to the casing and positioned adjacent said rotatable body, means connected between the casing and the movable means to bias said movable means toward said rotatable body, and thermal responsive means to automatically vary the position of said movable means in conjunction with said biasing means to compensate for changes in fluid viscosity to maintain a predetermined damping effect on the rotatable body.

20. A damping control for a rotatable body immersed rotatablebodyiresilient'means *connect'ed'to the shioud 'anld=contaeting' th'ecasing to'bia's the shroudltowa'rd the rotatablefii'ember'f' an'dmieans'enacting with'said biasing meansbetwee'if saidfree' end'of the shroud and the casing 'toautomaticallyjvary the spacing between the 'shioud and therotatable body 'to maintain' thereby 'a predetermined damping effect on the' body.

21. A damping control for a rotatable'body immersed in' a fluid-ffilled""easing "comprising a shroud pivotally -'-con r'lect'ed to thbasing," said shroud havingl'it's fre'end positioned along but o'litof eontact' with the surface of the-'rotatable'jbody; resilien'frneans'interconnected betv'veen the sh'rou'd and the casingto bias the'shroud to- Wai'd" thero'tatable member, and thermal responsive meanscoaetin'g' with said-biasing means between said free end of the shroudand the. casingito. automatically 1 'Ya'.ry thefspacirlgbejtweenthe sh roud ahd the rotatable body.- to'frn'eiinta'in the'rebyfa' predetermined damping effect on thefbody.

I) R'freh'Citd in the file'of' this patent m UNITED STATES PATENTS 

